The Siebens Building is a 220-foot (67 m) high-rise in Rochester, Minnesota, United States. It is built where the William Worrall Mayo home had been, and the original Mayo Clinic building was built on the site in 1914. The Siebens Building is operated by Mayo Clinic and is the center for educational activities and houses the Venables Health Science Library, classrooms and computer labs. The building also holds some Mayo Clinic administrative offices and study areas. The 14th floor—referred to as the "Greenhouse" for its glass, pitched ceilings or greenhouse-like look—is home to Mayo Clinic Volunteer Office.